The Republican presidential nominee was supposed to make his 13th appearance tonight on Letterman’s show, the venue where he originally announced his White House bid in 2007. But he backed out late Wednesday afternoon, saying he was suspending all campaign activities to focus on getting a financial bailout plan through Congress.

During the taping of tonight's show, Letterman told the audience that McCain had called him personally to apologize for standing him up and said he was rushing to the airport to get back to Washington. The late-night host called McCain “an honest-to-God hero,” and questioned why he needed to halt his campaign. Couldn’t his running mate, Sarah Palin, take over while he was in Washington, Letterman asked.

“I’m more than a little disappointed by this behavior,” he said. “We’re suspending the campaign. Suspending it because there’s an economic crisis, or because the poll numbers are sliding?”

The audience whooped and applauded.

“You don’t suspend your campaign,” Letterman added. “Do you suspend your campaign? No, because that makes me think, well, you know, maybe there will be other things down the road –- if he’s in the White House, he might just suspend being president. I mean, we've got a guy like that now!”

Incredulous, Letterman interrupted his chat with Olbermann to show the audience a live shot on the internal CBS news feed of McCain getting touched up by a makeup artist as he waited to talk to Couric.

“He doesn’t seem to be racing to the airport, does he?” Letterman said, shouting at the television monitor: “Hey John, I got a question! You need a ride to the airport?”

More highlights, including Letterman's Top Ten Questions People are Asking The John McCain Campaign after the jump...

-- Matea Gold

Photo: An earlier appearance by John McCain on "The Late Show with David Letterman." Courtesy CBS.

The Top Ten Questions People are Asking The John McCain Campaign

#10 “I just contributed to your campaign – how do I get a refund?

#9 “It’s Sarah Palin – does this mean I’m pars’dent?”

#8 “Can’t you solve this by selling some of your houses?”

#7 “This is Clay Aiken. Is McCain single?”

#6 “Do you still think the fundamentals of our economy are strong, Genius?”

#5 “Are you doing all of this just to get out of going on Letterman?”

#4 “What would Matlock do?”

#3 “Hillary here – my schedule is free Friday night.”

"It’ll be interesting here to see if Barack Obama feels the need to suspend his campaign to go down there and work on the economy. He’s also a senator. And his running mate, Joe Biden, he’s also a senator. So there, those two guys have to get back to work. So of course, they’ll suspend their campaign. Don’t you think?

"The Democrats are now at a real disadvantage because Barack Obama has got to race back and fix the economy. So does Joe Biden. He has to race back and fix the economy. But the republicans have Sarah Palin, the governor of Alaska. The Alaska economy is fine. It don’t need fixing. It’s fine. So she’ll continue the campaign. So the democrats are really in a hole now."

#2 “Is this just an excuse to catch up on napping?”

#1 “This is President Bush – what’s all this trouble with the economy?”

Letterman's extensive criticism continued:

We’re in sorry need and short supply of actual heroes like John McCain… But when you call up at the last minute and cancel a show…This is not the John McCain I know, by God. It makes me believe something is going haywire with the campaign. Someone got to him and said, blow Letterman off, he’s a lightweight.

Sure, there’s an economic crisis. And here’s what you’re do if you’re running your campaign in the middle of an economic crisis and its about to crater…You’re a fourth term senator from Arizona. You handle what you need to handle. Don’t suspend your campaign. You let your campaign go on, shouldered by your vice presidential nominee. That’s what you do…

You say, I gotta get back to Washington to save this country. Good for you. And while I’m gone, campaigning in my stead will be my great running mate from the state of Alaska, Sarah Palin. And she comes out and campaigns. What happened there? What’s the problem? Why isn’t she doing that?

This doesn't smell right. This just doesn’t smell right. Because this is not the way a tested hero behaves. I think someone's put something in his Metamucil.

And let’s say there’s a time of crisis, and the poor guy, because he’s a little older…Palin takes over as president, well, she ought to be ready, because she’s handled crisis like these in the past. Oh, wait a minute, she really hasn’t handled a crisis like this in the past.

He can't run the campaign because the economy is about to crater? Fine, you put in your second string quarterback. Well, where is there second string quarterback?

After Letterman learned that McCain was sitting down at that moment with Katie Couric, he had this to say:

I don’t want to keep beating this thing, but it just really is starting to smell now. Because he says to me on the phone, I took a phone call from John McCain – a lot of senators don’t call me – and so I felt like OK, as part of the national good, I understand and I said good luck and thank you for being attentive to the cause. And he said maybe next time I’ll come in and I’ll bring Sarah Palin. And I said, fine, whatever you need to do, that’s just fine. And he said, yeah, we’re going to go save the country. And then it’s like we caught him getting a manicure or something!